Fix removal of a single observed row in some cases; fixes #224
Fix removal of a single observed row in some cases; fixes #224

Thanks to @kriszyp for the suggested code change.

maier49/dgrid,dylans/dgrid,dylans/dgrid,dylans/dgrid,kfranqueiro/dgrid,kfranqueiro/dgrid,maier49/dgrid,kfranqueiro/dgrid,maier49/dgrid